METHANE DIGESTION OF CATTLE MANURE AT LOW-TEMPERATURES

An acclimatized methanogenic microbial association able to digest catt le manure at 6 degrees C was obtained by means of long-term (2.5 years ) autoselection. An extended period of microbial community adaptation was shown to be the main difficulty of low-temperature anaerobic diges tion; application of the acclimatized inoculum was shown to be a solut ion to the problem. The activity of the psychrophilic methanogenic ass ociation decreased two and ten times after it was cultivated under mes ophilic (35 degrees C) and thermophilic (55 degrees C) conditions, res pectively. A conclusion based on kinetic calculations is made that the anaerobic community undergoes significant transformations during adap tation to low temperature. The dominant part in processes of the low-t emperature degradation of organic matter in this ecosystem is assigned to psychrotrophic microflora. Pure cultures of psychrotrophic sacchar olytic and homoacetogenic bacteria able to grow within a wide temperat ure range (0 - 35 degrees C) were isolated. The presence of acetoclast ic Methanosarcina and Methanothrix was demonstrated in the studied low -temperature microbial community.